Organ walls are composed of several layers: the mucosa (the surface layer), the submucosa, the muscularis (muscle layer), and the serosa (connective tissue layer). In gastrointestinal, colonic, and esophageal cancer, for example, small lesions or cancerous masses may form along the mucosa and often extend into the lumens of the organs. Conventionally, that condition is treated by cutting out a portion of the affected organ wall. This procedure, however, may cause discomfort to patients, and pose health risks. Recently, physicians have adopted a minimally invasive technique called endoscopic mucosal resection (EMR), and another called endoscopic submucosal dissection, which removes the cancerous or abnormal tissues (e.g., lesions), keeping the walls intact.
EMR is generally performed with an endoscope, which is a long, narrow elongated member optionally equipped with a light, video camera, and other instruments. During EMR, the endoscope is passed down the throat or guided through the rectum to reach an abnormality such as a lesion in an affected organ. The distal end of the endoscope, further equipped with a cap carrying a small wire loop or a band, is guided towards the lesion. Once there, suction may be applied through a lumen in the elongated member, or some other retraction tool extending from the endoscope is retracted, to draw the lesion towards the endoscope cap. When the lesion is sufficiently drawn into the cap, the wire loop or band closes around the lesion, resecting it from the organ wall, or banding it. Subsequently, the excised tissue may be extracted by e.g., the vacuum, for examination, biopsy, or disposal.
Certain polyps, such as pedunculated polyps, are characterized by a stalk attached to the mucosal layer. Drawing such polyps into the cap, without drawing in any other tissue, is possible. Certain other polyps, such as sessile polyps, however, exhibit a broad base, and lay flat on the mucosal surface, devoid of a stalk. It is often difficult to grasp these polyps, without drawing in a part of the muscularis layer. Conventional EMR caps include axial channels for introducing devices proximate the affected area. Because polyps or lesions are present on the organ walls, it is often difficult to grasp such objects readily with axially extending devices and obtain a better vantage point to apply overhead lifting force.
Therefore, there exists a need for an improved endoscopic mucosal resection tool that aids in grasping and/or resecting both pedunculated and sessile polyps without damaging the surrounding tissue or muscle layers of the organ